1211210020721 has 4 divisors (see below), whose sum is σ = 1250281311744. Its totient is φ = 1172138729700.

The previous prime is 1211210020717. The next prime is 1211210020739. The reversal of 1211210020721 is 1270200121121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1211210020721 - 2² = 1211210020717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211210020693 and 1211210020702.

It is not an unprimeable number, because it can be changed into a prime (1211210020421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19535645465 + ... + 19535645526.

It is an arithmetic number, because the mean of its divisors is an integer number (312570327936).

Almost surely, 2^{1211210020721} is an apocalyptic number.

It is an amenable number.

1211210020721 is a deficient number, since it is larger than the sum of its proper divisors (39071291023).

1211210020721 is an equidigital number, since it uses as much as digits as its factorization.

1211210020721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39071291022.

The product of its (nonzero) digits is 112, while the sum is 20.

Adding to 1211210020721 its reverse (1270200121121), we get a palindrome (2481410141842).

The spelling of 1211210020721 in words is "one trillion, two hundred eleven billion, two hundred ten million, twenty thousand, seven hundred twenty-one".